A total of 10 hospitals in Ontario say they bought bulk IV medications from Marchese Hospital Solutions, a company linked to an underdosing of chemotherapy patients, a survey suggests.

After about 1,200 people in New Brunswick and Ontario received lower-than-intended doses of the chemotherapy drugs cyclophosphamide and gemcitabine, which were pre-mixed by Marchese Health Solutions, Ontario's Health Ministry asked the Ontario Hospital Association to survey its members about their reliance on external providers of pre-compounded IV medications, including chemo.

Hospitals are very engaged in the safety of their drug supply, says Ontario health minister Deb Matthews. (CBC)

The role of the Hamilton, Ont.-based owner of Marchese Hospital Solutions, is also under investigation. The company has said the problem occurred in how the intravenous bags of chemotherapy were administered at five hospitals, not in how they were prepared at the company's Mississauga facility.

The 88 hospitals that responded to the Ontario Hospital Association's survey represented 94 per cent of the province's acute care beds.

Of those 88 hospitals, 40 responded that they've purchased pre-compounded IV medications in a "ready-to-administer" form from external providers.

"The drugs we are concerned about right now [are] where the drugs are premixed in a large bulk format and then they're handled further in the hospital pharmacy to be prepared for individual patients," Pat Campbell, president and CEO of the Ontario Hospital Association, said in an interview Tuesday.

"There are 10 hospitals that are securing drugs in that way," aside from the hospitals in Peterborough, Oshawa, London and Windsor that faced the overdilution issue.

In the survey, the most common classes of pre-compounded IV medications purchased from an external provider were:

Chemotherapy, 7 per cent or six hospital respondents.

Narcotics, 2 per cent or two hospitals.

Epidurals, 2 per cent or two hospitals.

"Hospitals are very focused on this and they are looking at their quality assurance that's in place now," Ontario Health Minister Deb Matthews told reporters.

Hospitals said the main reason they compounded in bulk was for occupational health and safety, given how toxic the drugs are, Campbell said.

The four Ontario hospitals where patients received overdiluted chemotherapy have all said they no longer purchase bulk IV medications.

Health Canada and the provinces and territories are working to improve oversight, including inspections, of companies that aren't federally licensed as manufacturers or provincially accredited as pharmacies.

The work of investigators and the acceleration of regulations are happening now, Matthews said. "Hospitals are very engaged in the safety of their drug supply."